I don't know "key_gen" -- but whatever it is, it may require you to use it with an option in to create keys in OpenSSH format. There are other SSH servers, and OpenSSH may not be the default. Check by comparing the contents of a .pub file generated by "key_gen" with one you create using ssh-keygen(1). Different file format, or the same?

Another possibility: PermitRootLogin may be set to no. See sshd_config(5).

Of course you have already done a #ls -l /root/.ssh to confirm the file is in the right place with the right permissions?

Edited to add:

And on the client, you've also examined $HOME/.ssh to ensure both key files are in place, with the right permissions?

I think you need -vv, or perhaps you need to look at /var/log/authlog on the host for additional information. It appears that the RSA key was offered but authentication could not be made. See two lines above your highlighting.

I think you need -vv, or perhaps you need to look at /var/log/authlog on the host for additional information. It appears that the RSA key was offered but authentication could not be made. See two lines above your highlighting.

I am not sure why it is offering the .pub key. That key was copied over to the server. Or I guess the it's the server offering the public key? I can't differentiate which line belongs to which host.

Do I need to create the key with the user I am trying to log in with (i.e. create with root user)? (I created the keys with a regular user on my mac)

Do I need to create keys on the SSHd server (openBSD) or the remote machine (my mac) or does that matter?